Objectives. To determine the in-vivo anti-Trypanosoma cruzi activity of the essential oil from Aloysia triphylla in mice. Materials and methods. The mice (n = 15) in the study were randomly assigned to the following groups: infected and untreated (G1), infected and treated with benznidazole 100 mg/kg (G2), infected and treated with of Aloysia triphylla essential oil 100 mg/kg (G3), infected and treated with of Aloysia triphylla essential oil 250 mg/kg (G4), uninfected and untreated (G5), and uninfected and treated with 250 mg/kg of Aloysia triphyla (G6). The infection was conducted using 104 blood T. cruzi trypomastigotes and the treatment began on the 8th day post-infection (dpi) through 28 dpi. The parasitemia was determined through optical microscopy every 2 days using 5 μL of blood sampled from the tail. In dpi 14, 21 and 28, the blood sample was obtained from the queue for testing creatine kinase-MB, alanine aminotransferase and creatinine, then animals were euthanized and the heart was removed for histopathological study. Results. The essential oil of lemon verbena produced a significant reduction of the parasitemia, 85.4% with the peak at a the dose of 250 mg/ kg. It was also observed a reduction in the number of amastigotes and inflammatory infiltrates in the heart. The creatine kinase-MB plasma levels also decreased at dpi 28 as a result of such treatment. Conclusions. Under experimental conditions, the essential oil of Aloysia triphylla (lemon verbena) has in vivo anti-Trypanosoma cruzi effect in mice